CN102547902A - Multipath routing method for Ad-Hoc network based on planar region division - Google Patents

Abstract

The invention discloses a multipath routing method for the Ad-Hoc network based on planar region division. A source node is used for calculating the distance between the source node and a destination node, all plane surfaces, on which all nodes in the network locate, are divided into nonoverlapping regions, the number of the regions and the number of corresponding curves are determined, and the coefficient of curvilinear equation is computed; the source node can write geography information of the source node and the destination node, as well as the coefficient of curvilinear equation into the head of a data packet, and forwarding to a next hop node is carried out according to a routing forward strategy; after a forwarding node receives the data packet, the geography information of the source node and the destination node, as well as the coefficient of curvilinear equation are taken out from the head of the data packet, self locating region is determined, and forwarding is continuously performed according to the routing forward strategy; then forwarding is performed by a follow-up forwarding node according to the method until the data packet reaches a target node. According to the invention, multiple paths can be built in the divided nonoverlapping regions by using the position information of nodes, not only the nonoverlapping property of nodes is considered, but also spending on route discovery caused by simple flooding is avoided, and the route discovery efficiency is improved.

Description

A kind of Ad Hoc network multipath routing method of dividing based on plane domain

Technical field

The present invention relates to the Ad Hoc network multipath routing method of technical field of the computer network, particularly a kind of Ad Hoc network multipath routing method of dividing based on plane domain.

Background technology

Ad Hoc network (self-organizing network) is the dynamic syndicated body that does not rely on the mobile node of any static infrastructure.Because have the advantages such as high spreadability of infrastructureless support, high dynamic, radio communication and multi-hop transmission, Ad Hoc network is with a wide range of applications in fields such as military applications, disaster assistances.Yet characteristics such as the high dynamic that Ad Hoc network itself has, multi-hop transmission, finite energy property make and ensure that reliable transfer of data becomes a key and stubborn problem.

With respect to traditional single footpath route, the multipath route has become the focus in the research of self-organizing network route realizing having very strong advantage aspect load balancing, raising route reliability and the fault-tolerance.The multipath route implementing is effective assurance of Ad Hoc network reliability service.The multipath route is utilized the redundancy of multilink, improves the reliability of dynamic change system.In addition, in a route finding process, find mulitpath, can reduce the route discovery number of times, and reduce traditional error control expense and end-to-end delay, improve network real-time property.Use after the multipath,, reduced the energy consumption of intermediate node on this path, also help improving real-time originally concentrating on load allocating on the paths on several different paths.The multipath route can adapt to the easy characteristics that lost efficacy of node in the wireless network, thereby utilizes network topological information preferably.

The multipath technology is divided into according to the multipath occupation mode uses individual paths and concurrent use mulitpath pattern successively, is divided into crossing multipath, the non-intersect multipath of link and the non-intersect multipath model of node according to the path correlation.The non-intersect multipath of node can make full use of Internet resources, reaches load balancing, but also the most difficult searching.

Present multipath route generally is on the basis of single path route (like dynamic source routing protocol DSR and self-organizing network distance vector routing protocol AODV as required), to expand; As: separating multiple diameter route (split multipath routing; SMR), as required multipath distance vector route (ad hoc on-demand multipath distance vector, AOMDV); Based on the Routing Protocol of ballot paper mode (ticket based routing protocol, TBR).Can there be the problem of broadcast storm in these several kinds typical multipath Routing Protocols in being applied to large-scale network environment, and existing most of method for routing does not utilize the geographical location information of node to seek many road warps fully yet.

Summary of the invention

The object of the invention is to provide a kind of quick foundation routing algorithm of non-intersect multipath to greatest extent.

The technical solution that realizes the object of the invention is:

1) distance between source node calculating self and the destination node; The plane at all node places in the network is divided into disjoint zone through elliptic curve; Path bar number is as required confirmed the number and the corresponding curved line number in zone, calculates the coefficient of each curvilinear equation then;

2) source node is with the geographical location information of self and destination node; And the curvilinear equation coefficient writes the packet head; And in packet head interpolation access path field, be used for storing local access path, transmit to next-hop node based on the routing forwarding strategy then;

3) after forward node is received packet, take out the geographical location information of source node and destination node from packet header, and the curvilinear equation coefficient, judge self region, and continue to transmit according to the routing forwarding strategy;

4) follow-up forward node continues to transmit according to the said method of step 3, arrives destination node until packet.

Wherein the method for calculated curve equation coefficient is following:

1) distance between calculation sources node and the destination node.Source node S obtains the geographical position coordinates D (x of destination node D through location-based service (Location Service) _D, y _D), the geographical position coordinates of source node S is S (x _S, y _S).Through range formula calculation sources node between 2 o'clock and the distance between the destination node $d=\sqrt{(x_D-x_S{)}^2+(y_D-y_S{)}^2}.$

2) definite curved line number that needs.When path bar number is k; Need

bar curve; Here straight line y=0 and elliptic curve

are referred to as curve; Work as a; B equals at 0 o'clock, and curvilinear equation is y=0.

3) coefficient of calculated curve equation.According to the parity that required path bar is counted k, select the coefficient in the equation

of different formula calculated curves.If k is an odd number, then select formula $a_0=a_1=a_2=L{a}_{n-1}=\frac{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA0000131889950000012.png"\; state="\{\{state\}\}">d</figure-callout>}}{2},$ $b_i=\frac{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000131889950000012.png"\; state="\{\{state\}\}">h</figure-callout>}}{2}+\mathrm{Ih}(0\&le;i\&le;n-1,i\&Element;N),$ $h=\frac{\mathrm{Cd}}{k},$ C is a constant, calculates n curvilinear equation coefficient to (a _i, b _i) (0≤i≤n-1, i ∈ N); If k is an even number, select formula

b _i=ih (1≤i≤n-1, i ∈ N),

Calculate n-1 curvilinear equation coefficient to (a _i, b _i) (1≤i≤n-1, i ∈ N), for a ₀, b ₀, make a ₀=0, b ₀=0, promptly curvilinear equation is y=0.

Wherein the method for decision node affiliated area is following:

Because the geographical position that node obtains through GPS equipment is the coordinate in the latitude and longitude coordinates system; And the coordinate system of curve is as initial point with source node; Arrive the rectangular coordinate system of the directed line of destination node D with source node S as the x axle; Both are different coordinate systems, so need carry out coordinate transform.The present invention is regarded as being positioned at same plane with all nodes; So can regard latitude and longitude coordinates system as rectangular coordinate system; And be called coordinate system Oxy; Will be with source node as initial point, the rectangular coordinate system of setting up as the x axle to the directed line of destination node D with source node S is called coordinate system O ' x ' y ', and coordinate transform is shown in formula (1).

$\left\{\begin{array}{c}{x}^{\&prime;}\text{=}(x-x_0)\cos \mathrm{\&theta;}+(y-y_0)\sin \mathrm{\&theta;}\\ y^{\&prime;}=-(x-x_0)\sin \mathrm{\&theta;}+(y-y_0)\cos \mathrm{\&theta;}\end{array}\right.---\left(1\right)$

(x wherein ₀, y ₀) be exactly the coordinate (x of source node S in coordinate system Oxy _S, y _S), θ is the angle of Ox axle and O ' x ' axle, i.e. vector

$\sin \mathrm{\&theta;}=\left\{\begin{array}{c}\sqrt{1-\mathrm{<figure-callout\; id="2"\; label="co\; s"\; filenames="HDA0000131889950000012.png"\; state="\{\{state\}\}">co</figure-callout>}{s}^{}{}^2\mathrm{\&theta;}},y_D>y_S\\ -\sqrt{1-{\cos }^2\mathrm{\&theta;}},y_D<y_S\end{array}\right.---\left(3\right)$

According to formula (4) and formula (5) respectively the calculating path bar to count k be whether the situation lower node of odd and even number belongs to appointed area, wherein M _iBe the zone number of zoning at first quartile, M _-iFor the zoning at four-quadrant zone number.The appointed area refers to the zone that the curve that is determined is surrounded from the curve coefficients of packet head taking-up.

The algorithm whether concrete decision node belongs to the appointed area is following:

1) node is received after the packet, from the packet head, takes out source node coordinate (x _S, y _S), destination node coordinate (x _D, y _D) and the coefficient a of two boundary curves in appointed area _i, b _i, a _I+1, b _I+1

2) use formula (1), (2), (3) can calculate node through the curvilinear coordinate after the coordinate transform (x ', y ');

3) with curvilinear coordinate (x ', y ') substitution formula (4) or formula (5), upright if inequation is formed, explain that then node is in the appointed area; Otherwise, explain that node is outside the appointed area.

Wherein the routing forwarding strategy is following:

Forward mode and sideline forward mode are realized in the said routing forwarding strategy calmodulin binding domain CaM.The node that receives packet judges whether oneself drops in the appointed area, if then transmit data according to forward mode in the zone; Otherwise, transmit data according to the sideline forward mode.The present invention is used for storing local access path in the access path field that the packet head adds, in case the generation of loops, and the forward mode under the auxiliary judgment.Concrete adding method is the node address (32) in the afterbody interpolation access path of packet head, and revises the data packet length field.

1) the greedy forwarding strategy that weakens

The forwarding strategy of mentioning in the forwarding strategy that the present invention adopts and classical GPSR (the Greedy Perimeter Stateless Routing) agreement is different; The each next-hop node of selecting of forward node is not necessarily than present node more near the node of destination node; So long as get final product near the node of destination node in the neighbor node set, we claim that this greedy forwarding is the greedy forwarding of reduction.Present node then is in normal condition if can find than self more near the neighbor node of destination node, and empty access path field earlier this moment, again with self writing wherein, selects then to transmit data near the neighbor node of destination node.If all neighbor nodes all than present node further from destination node, then be in the situation of local optimum, claim that present node is the local optimum node.Take place after the local optimum situation; When selecting next-hop node, subsequent node all to judge the position of next-hop node and local optimum node earlier; If next-hop node is more near destination node; Explanation can be jumped out the situation of local optimum, then earlier the access path field is emptied, again with self writing wherein; Otherwise directly with self adding in the access path field, in case the generation of loops.Weaken greedy forwarding strategy when running into the situation of local optimum, can walk around hole region effectively.

2) forward mode in the zone

Present node is sought in the zone than self more near the neighbor node of destination node, normally transmit if find then, otherwise in gathering according to the greedy forwarding strategy searching of reduction neighbor node near the node of destination node.This node might be in the zone, also might be outside the zone.If in the appointed area, then continue to transmit according to forward mode in the zone; If outside the zone, then switch to the sideline forward mode.

3) sideline forward mode

Call this regional sideline to the sending zone near the curve of x axle.Node is received after the packet; In the appointed area and than first node in the access path field, more seek earlier near the zone of destination node; If node is arranged, then earlier the access path field is emptied, again with self writing wherein; Select to transmit near the node of destination node, switch to forward mode in the zone then; If do not have, just outside the appointed area and more near selection in the scope of destination node near the node in sideline, appointed area, make data forwarding can get back to original appointed area as soon as possible.This moment is for the generation of anti-loops, directly with self adding in the access path field.If still do not find node, just outside the appointed area, select to jump as next near the node of destination node according to the greedy forwarding strategy of reduction.At this moment, also will be with self adding in the access path field.The purpose of " paying the utmost attention to the node that can get back to the appointed area jumps as next " is to avoid the path to intersect as far as possible under the forward mode of sideline, or when occurring intersecting, breaks away from crossing as early as possible.

The present invention compared with prior art; Its remarkable advantage: the present invention makes full use of node location information, in the disjoint range of dividing, constructs mulitpath, has both considered the non-intersect property of node; The route discovery expense that having avoided again simply floods brings has improved the efficient of path finding.The greedy forwarding strategy that weakens do not require next-hop node than present node more near destination node, can walk around hole region effectively.If when in the appointed area, can not find node, just detour from the zone, next door, guarantee under the sparse situation of node, also can successfully find the path.Launch the sideline forward mode and can make data forwarding get back to original appointed area as soon as possible, avoid the path to intersect as far as possible, or when occurring intersecting, break away from crossing as early as possible.

Description of drawings

Fig. 1 is an even number paths area dividing sketch map.

Fig. 2 is an odd number paths area dividing sketch map.

Fig. 3 is an overview flow chart of the present invention.

Fig. 4 is for calculating the flow chart of zoning curvilinear equation.

Fig. 5 (a) is a forwarding strategy sketch map under the interior forward mode normal condition in zone, forwarding strategy sketch map under the forward mode local optimum situation in Fig. 5 (b) zone.

Fig. 6 is a forwarding strategy sketch map under the forward mode of sideline.

Fig. 7 is a forward mode algorithm flow chart in the zone.

Fig. 8 is a sideline forward mode algorithm flow chart.

Embodiment

The present invention constructs the multipath route and is achieved in that all nodes in the network are regarded as being positioned on the same plane domain; Utilize GPS equipment to obtain the geographical location information of node; On this plane, be divided into disjoint zone, seeking a paths in the zone separately respectively then through elliptic curve.If can not find next-hop node in the one's respective area, just be transmitted to the node of adjacent area, and in continuing the process of transmitting wraparound one's respective area as soon as possible.This method guarantees under the intensive situation of node, can construct the non-intersect multipath of node; Under the sparse situation of node, also can find and intersect the least possible multipath, it is the least possible promptly to intersect path bar number, and the crossed node number is the least possible.

Below in conjunction with accompanying drawing the present invention is described in further detail.

Fig. 1 and Fig. 2 are respectively under the situation of odd and even number paths, according to the plane domain division methods of the present invention's proposition.As initial point, set up rectangular coordinate system to the directed line of destination node as the x axle with source node, with the geographical position of node in the coordinate representation network of this coordinate system with source node.Cross destination node and make the straight line of a vertical x axle, divide the y axle to the belt-like zone M between this vertical line.The present invention adopts elliptic curve to carry out area dividing.

When node distributed relatively evenly in the network, the present invention designed and divides the every region area S of coming out _iEqually big, can make the node number that distributes in the every zone similar like this, can both find the path to guarantee every zone.

Need to suppose structure k paths.If k is an even number; Then need

bar elliptic curve and straight line; Be respectively

i=1; 2; ..., n-1 and y=0.Because four-quadrant and first quartile axial symmetry, we only discuss the situation of first quartile here.Because

And

In order to make S ₁=S ₂=L=S _N-1, can draw b ₁=b ₂-b ₁=L=b _N-1-b _N-2, make it equal constant h, i.e. a b _i=ih (1≤i≤n-1, i ∈ N).

If k is an odd number, need The bar elliptic curve is respectively

I=0,1,2 ..., n-1 and

Wherein, regional M ₀Be elliptic curve

Interior zone, regional M _i(1≤i≤n-1) is the zone between i-1 bar curve and the i bar curve.At this moment, $b_i=\frac{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000131889950000012.png"\; state="\{\{state\}\}">h</figure-callout>}}{2}+\mathrm{Ih}(0\&le;i\&le;n-1,i\&Element;N).$

Make

wherein; C is a constant; D be source node to the distance between the destination node, k is for needing the multipath bar number of structure.

Describe the operating mechanism of forward mode and sideline forward mode in the zone in detail in conjunction with Fig. 5 and Fig. 6.

In Fig. 5 (a) figure, node A is a present node, and Node B is to have the unique node in the access path field in the packet head.Zone M_in representes to drop in the node A communication radius zone of transmitting in the zone, and regional M_out representes to drop on the extra-regional zone of forwarding.Zone M_in_c is illustrated among the regional M_in than node A more near the zone of destination node, and regional M_in_f is illustrated among the regional M_in than node A from the farther zone of destination node.In like manner, regional M_out_c is illustrated among the regional M_out than node A more near the zone of destination node, and regional M_out_f is illustrated among the regional M_out than node A from the farther zone of destination node.

In Fig. 5 (b) figure, node A is a present node, and Node B is to have first node in the access path field in the packet head.The implication of zone M_in, M_out, M_out_f, M_out_c is identical with the middle expression of figure (a); M_in_f, M_in_c are different with figure (a) in the zone; Zone M_in_c is illustrated among the regional M_in than Node B more near the zone of destination node, and regional M_in_f is illustrated among the regional M_in than Node B from the farther zone of destination node.

Among Fig. 6, node A is a present node, and Node B is first node in the access path field in the packet head, and the division of (b) figure among the division of regional M_in, M_out, M_out_f, M_out_c, M_in_f, M_in_c and Fig. 5 is identical.

The forward mode algorithm is following in the zone:

1) node A judges whether first node belongs to the appointed area in the access path field, if explain that a hop node is in forward mode in the zone, forwards 2 to); Otherwise, explain that a hop node is in the sideline forward mode, forwards 3 to);

2) node A judge self whether than first node in the access path more near destination node, if explain to be in normal condition, forward 3 to); Otherwise, be in the local optimum situation, forward 4 to);

3) judge Fig. 5 (a) figure in the M_in_c zone in whether have node, if forward 5 to); Otherwise, forward 6 to);

4) judge Fig. 5 (b) figure in the M_in_c zone in whether have node, if forward 5 to); Otherwise, forward 6 to);

5) empty the access path field, and, select then to transmit as next-hop node near the neighbor node of destination node in the M_in_c zone, finish self adding in the access path field;

6) node A does not consider earlier the node in the access path, selects to jump as next near the neighbor node of destination node.Judge then whether first node belongs to the appointed area in the access path field, if forward 7 to); Otherwise, forward 8 to);

7) node A judge self whether than first node in the access path more near destination node, if forward 8 to); Otherwise, directly self is added in the access path, and packet is sent to next jumping, finish;

8) empty access path earlier, with self adding in the access path, then packet is sent to next jumping again, finish.

Sideline forward mode algorithm is following:

1) node A judges in the M_in_c zone among Fig. 6 whether have node, if forward 2 to); Otherwise, forward 3 to);

2) empty the access path field, and, select then to transmit as next-hop node near the neighbor node of destination node in the M_in_c zone, finish self adding in the access path field;

3) node A judges in the M_out_c zone among Fig. 6 whether have node, if forward 4 to); Otherwise, forward 5 to);

4) with oneself adding in the access path field, select then to transmit as next-hop node near the node in sideline, appointed area in the M_out_c zone, finish;

5) in the M_out_f zone among judgement Fig. 6, remove the node in the access path field, whether also have other nodes) if forward 6 to; Otherwise the data forwarding failure finishes;

6) with self adding in the access path field, in the M_out_f zone, do not consider the node in the access path then, select to transmit as next-hop node near the node of destination node, finish.

Claims (5)

1. Ad Hoc network multipath routing method of dividing based on plane domain is characterized in that method is following:

1) distance between source node calculating self and the destination node; The plane at all node places in the network is divided into disjoint zone through elliptic curve; Path bar number is as required confirmed the number and the corresponding curved line number in zone, calculates the coefficient of each curvilinear equation then;

2) source node writes the packet head with the geographical location information and the curvilinear equation coefficient of self and destination node; And in packet head interpolation access path field; Be used for storing local access path, transmit to next-hop node according to the routing forwarding strategy then;

3) after forward node is received packet, take out the geographical location information and the curvilinear equation coefficient of source node and destination node, judge self region, continue to transmit according to the routing forwarding strategy then from packet header;

4) follow-up forward node continues to transmit according to the said method of step 3, arrives destination node until packet.

2. the Ad Hoc network multipath routing method of dividing based on plane domain according to claim 1, it is characterized in that: the method for calculated curve equation coefficient is following:

1) distance between calculation sources node and the destination node; Source node S obtains the geographical position coordinates D (x of destination node D through location-based service _D, y _D), the geographical position coordinates of source node S is S (x _S, y _S); Through range formula calculation sources node between 2 o'clock and the distance between the destination node $d=\sqrt{(x_D-x_S{)}^2+{(y_D-y_S)}^2}$

2) definite curved line number that needs; When path bar number is k; Need

bar curve; Straight line y=0 and elliptic curve

are referred to as curve; Work as a; B equals at 0 o'clock, and curvilinear equation is y=0;

3) coefficient of calculated curve equation; According to the parity that required path bar is counted k, select the equation of different formula calculated curves

In coefficient; If k is an odd number, then select formula $a_0=a_1=a_2=L{a}_{n-1}=\frac{d}{2},$ $b_i=\frac{h}{2}+\mathrm{Ih}(0\&le;i\&le;n-1,i\&Element;N),$ $h=\frac{\mathrm{Cd}}{k},$ C is a constant, calculates n curvilinear equation coefficient to (a _i, b _i) (0≤i≤n-1, i ∈ N); If k is an even number, select formula

b _i=ih (1≤i≤n-1, i ∈ N),

Calculate n-1 curvilinear equation coefficient to (a _i, b _i) (1≤i≤n-1, i ∈ N), for a ₀, b ₀, make a ₀=0, b ₀=0, promptly curvilinear equation is y=0.

3. the Ad Hoc network multipath routing method of dividing based on plane domain according to claim 1 is characterized in that the method for decision node affiliated area is following:

Look all nodes and be positioned at same plane; System regards rectangular coordinate system as with latitude and longitude coordinates; Be called coordinate system Oxy; Will be with source node as initial point, the rectangular coordinate system of setting up as the x axle to the directed line of destination node D with source node S is called coordinate system O ' x ' y ', and coordinate transform is shown in formula (1):

$\left\{\begin{array}{c}{x}^{\&prime;}\text{=}(x-x_0)\cos \mathrm{\&theta;}+(y-y_0)\sin \mathrm{\&theta;}\\ y^{\&prime;}=-(x-x_0)\sin \mathrm{\&theta;}+(y-y_0)\cos \mathrm{\&theta;}\end{array}\right.---\left(1\right)$

Wherein, (x ₀, y ₀) be the coordinate (x of source node S in coordinate system Oxy _S, y _S), θ is the angle of Ox axle and O ' x ' axle, i.e. vector

$\sin \mathrm{\&theta;}=\left\{\begin{array}{c}\sqrt{1-\mathrm{co}{s}^2\mathrm{\&theta;}},y_D>y_S\\ -\sqrt{1-{\cos }^2\mathrm{\&theta;}},y_D<y_S\end{array}\right.---\left(3\right)$

According to formula (4) and formula (5) respectively the calculating path bar to count k be whether the situation lower node of odd and even number belongs to the appointed area; M wherein _iBe the zone number of zoning at first quartile, M _-iFor the zoning at four-quadrant zone number; The zone that the appointed area surrounds the curve that is determined for the curve coefficients of taking out from the packet head;

It is following whether decision node belongs to the specific algorithm of appointed area:

1) node is received after the packet, from the packet head, takes out source node coordinate (x _S, y _S), destination node coordinate (x _D, y _D) and the coefficient a of two boundary curves in appointed area _i, b _i, a _I+1, b _I+1

2) use formula (1), (2), (3) can calculate node through the curvilinear coordinate after the coordinate transform (x ', y ');

3) with curvilinear coordinate (x ', y ') substitution formula (4) or formula (5), upright if inequation is formed, then node is in the appointed area; If the inequation group is false, then node is outside the appointed area.

4. the Ad Hoc network multipath routing method of dividing based on plane domain according to claim 1 is characterized in that the described routing forwarding strategy of step 2 and step 3 is following:

Forward mode and sideline forward mode are realized in the said routing forwarding strategy calmodulin binding domain CaM; The node that receives packet judges whether oneself drops in the appointed area, if then transmit data according to forward mode in the zone; Otherwise, transmit data according to the sideline forward mode; The concrete grammar that adds the access path field at the packet head is: the afterbody at the packet head adds 32 node addresss in the access path, and revises the data packet length field;

The forward mode method is following in the zone:

Present node is sought in the zone than self more near the neighbor node of destination node, normally transmit if find then, otherwise in gathering according to the greedy forwarding strategy searching of reduction neighbor node near the node of destination node;

Sideline forward mode method is following:

Call this regional sideline to the sending zone near the curve of x axle; Node is received after the packet; In the appointed area and than first node in the access path field, more seek earlier near the zone of destination node; If node is arranged, then earlier the access path field is emptied, again with self writing wherein; Select to transmit near the node of destination node, switch to forward mode in the zone then; If do not have, just the appointed area outside and more near selection in the scope of destination node near the node in sideline, appointed area, at this moment directly with self adding in the access path field; If still do not find node, just outside the appointed area, select to jump as next near the node of destination node according to the greedy forwarding strategy of reduction; At this moment, also will be with self adding in the access path field.

5. according to claim 1 or the 4 described Ad Hoc network multipath routing methods of dividing based on plane domain, the greedy forwarding strategy that it is characterized in that weakening is following:

Said reduction forwarding strategy is the node of from neighbor node set, selecting near destination node; Present node then is in normal condition if can find than self more near the neighbor node of destination node, and empty access path field earlier this moment, again with self writing wherein, selects then to transmit data near the neighbor node of destination node; If all neighbor nodes all than present node further from destination node, then be in the situation of local optimum, claim that present node is the local optimum node; Take place all will judge the position of next-hop node and local optimum node when subsequent node is selected next-hop node earlier after the local optimum situation, if next-hop node more near destination node, then earlier empties the access path field, again with self writing wherein; Otherwise directly with self adding in the access path field.

Images